Messages in this thread Patch in this message | | | Date | Tue, 28 Oct 2014 04:09:27 -0700 | From | tip-bot for Peter Zijlstra <> | Subject | [tip:sched/core] locking/mutex: Don't assume TASK_RUNNING |
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Commit-ID: 6f942a1f264e875c5f3ad6f505d7b500a3e7fa82 Gitweb: http://git.kernel.org/tip/6f942a1f264e875c5f3ad6f505d7b500a3e7fa82 Author: Peter Zijlstra <peterz@infradead.org> AuthorDate: Wed, 24 Sep 2014 10:18:46 +0200 Committer: Ingo Molnar <mingo@kernel.org> CommitDate: Tue, 28 Oct 2014 10:55:08 +0100
locking/mutex: Don't assume TASK_RUNNING
We're going to make might_sleep() test for TASK_RUNNING, because blocking without TASK_RUNNING will destroy the task state by setting it to TASK_RUNNING.
There are a few occasions where its 'valid' to call blocking primitives (and mutex_lock in particular) and not have TASK_RUNNING, typically such cases are right before we set TASK_RUNNING anyhow.
Robustify the code by not assuming this; this has the beneficial side effect of allowing optional code emission for fixing the above might_sleep() false positives.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: tglx@linutronix.de Cc: ilya.dryomov@inktank.com Cc: umgwanakikbuti@gmail.com Cc: Oleg Nesterov <oleg@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/20140924082241.988560063@infradead.org Signed-off-by: Ingo Molnar <mingo@kernel.org> --- kernel/locking/mutex.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c index dadbf88..4541951 100644 --- a/kernel/locking/mutex.c +++ b/kernel/locking/mutex.c @@ -378,8 +378,14 @@ done: * reschedule now, before we try-lock the mutex. This avoids getting * scheduled out right after we obtained the mutex. */ - if (need_resched()) + if (need_resched()) { + /* + * We _should_ have TASK_RUNNING here, but just in case + * we do not, make it so, otherwise we might get stuck. + */ + __set_current_state(TASK_RUNNING); schedule_preempt_disabled(); + } return false; }
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